To find out if some app is spying on you, you can use an ad hoc application. Here's how Access Dot works
For several years, Android smartphones have been targeted by various types of malware that use the phone's hardware, especially the camera and microphone, to spy on the user. They install themselves in the background and, without us noticing, record audio and video or take photos.
Google has tried to limit these practices and protect Android users by introducing in its operating system, version after version, an increasingly stringent policy regarding permissions granted to apps. On Android 10, for example, you can now grant access to the camera and microphone only when the app is running. And you can choose a different policy for each app. Apple is doing even more: with the upcoming iOS 14, an indicator will debut that will show the user if any app is accessing the microphone and camera. If the indicator lights up, but it's unclear for what reason, then there's some app that's accessing the photo/video camera in the background. Maybe to spy on us. When will such an indicator arrive on Android? It's already there, but you have to download the Access Dots app.
Access Dots: how it works
After installing Access Dots you need to go into Settings > Accessibility and tap on the app icon, then activate "Use the service". At this point Access Dots can start doing its job: showing a small green dot when it detects a camera access and a small orange dot when it detects a microphone access. You can choose the color of the indicators and where to place them (but only in the corners of the screen). The app, developed in India, does nothing more than that. But it does it just fine.
What to do if you turn on the indicator
What if Access Dots indicates to us that an app is using microphone or camera, but we don't understand which app it is? We need to investigate, because unfortunately Access Dots also doesn't tell us which app it is. So you need to check which apps are open in the background and, right after that, check the permissions granted to these apps. If one or more of these apps have granted access (always) to microphone or camera then it's very likely that they're the ones causing the indicator to light up. Otherwise, it's possible that there's something else running in the background and accessing the smartphone hardware. And this something else could be a virus.