There are a few ways to detect hidden cameras listening devices on your iPhone. One way is to use the built-in camera to take a picture of the device and then use the free app, FaceTime, to see if there is a face recognition icon next to it. If there is, then the device is likely listening in on your conversations. Another way is to use an app like iBeacon or Nest Cam that sends data about movement and sound from devices in your area.
