Call Incognito Investigative Services, LLC, and book a consultation.

She rings the number.
"Incognito Investigative, how may I help you?" a man's voice answers.
"Hi, think I'd like to book a consultation," she says, "how long do they usually take?"
"Maybe 15 minutes? It varies, but it shouldn't take long," the man replies.
"Do you have anything available between midday and 1pm today?" she asks.
"Sure. 12pm?"
"Actually, better make it twelve fifteen. I've got to drive from work," she realizes.
"No problem," the voice replies, "What name do you want on the booking?"
"Cynthia Michaelson," she says. She wonders if she should maybe use her maiden name or something, but before she can think too much about it -
"Alright, you've got a 12:15pm booking for Michaelson. See you there."

The offices of Incognito Investigative Services are located above a convenience store. As Cynthia walks down the narrow hallway to their office, she notices that there are two other office spaces up here - a piercing studio and, rather conveniently, a divorce lawyer. As she enters the door to IIS, LLC, the first thing she notices is how incredibly small the waiting room is. It'd be hard not to notice. Three empty chairs are crowded together with very little space to spare. The reception desk less a desk and more a podium with a stool behind it, also empty. The opening of the door rings a string of bells which hang over the frame, and movement can be heard behind the other door in the room, a door marked "Aaron Roussard, PI".
"Ms Michaelson! Please, take a seat and I'll be with you in a minute!" a voice rings out from beyond the door. Cynthia sits down, having second thoughts about her decision to come here. Oh well, she thinks, the consultation's free. Worst-case scenario, I waste my lunch break.

After a minute or so, the door opens, and a man appears.
"Alright Ms Michaelson, right this way," his expression is eager and friendly, although he seems almost caught off guard by Cynthia's presence. She stands up, offering her hand to shake.
"Cynthia," she introduces herself.
"Aaron Roussard," the man says, shaking her hand vigorously. Cynthia notices that his left wrist is in a cast. They enter his office, which is only slightly bigger than the waiting room and has a distinctly lived-in feeling about it. As she sits down, Cynthia can't help but notice packets of instant noodles stacked high beside an electric kettle on top of a filing cabinet beside Roussard's desk.
"So," says Roussard, sitting down behind the desk, "What brings you to Incognito Investigative?"
"Well..." Cynthia realizes she doesn't know where to start, "First, can I trust you not to tell anyone? I don't know what I'd do if people found out about this."
"I've never gone around gossiping about any of my previous clients, I don't know why I'd start now. You see this?" he holds up his hand in the cast, "I can't even tell you how I got this, that's how much I value discretion."
"I guess that's about as good a guarantee as I'm going to get," Cynthia sighs, "Okay. So, I recently found out that my husband, Mark, is cheating on me with my best friend Vanessa."
"What makes you think he might be cheating on you?" Roussard asks.
"I saw them fucking," Cynthia replies flatly, "Saw them, heard them, and heard them again on a different occasion. There's no doubt that they're having an affair, that's not why I'm here. I'm here because... have you by any chance heard of an app called iCock?"

Roussard's eyebrows raise.
"I've seen the news segments about women controlling men's penises with their phones, yes," he says.
"Well, I was randomly selected as a beta tester on the same day that I found out Mark was cheating on me, and since then I've been using it to-"
"I'm going to cut you off right there," interrupts Roussard, "Ms Michaelson, do you know what apophenia is?"
"No, what is it?"
"It's the tendency of our brains to see patterns and connections where there aren't any. Ms Michaelson, before I became a private investigator I was in advertising. This iCock thing is very clearly a viral marketing campaign, and in due time I'm sure we'll find out what for. Now, whatever changes you've perceived in your husband since downloading this app, the ones you're attributing to ultrasonic tones? I assure you, they're random occurrences that simply seem like they're being caused by the app," he says.
"I'm not imagining it," Cynthia frowns, "and these aren't small changes we're talking about."
"Come on, Ms Michaelson. Isn't the idea of an app that controls dicks a bit far-fetched?"

Cynthia doesn't respond. Instead, she takes out her phone, opens iCock and selects the cock belonging to Roussard.