To see which apps have access to your camera and microphone, go to System Preferences > Security & Privacy and click the Privacy tab at the top. And should you ever get the creepy feeling like someone is watching (or listening to) you, you can review which apps have permission to access your Mac's webcam or microphone. After updating to Mojave, apps will begin asking to use your camera or microphone. You've undoubtedly received notifications on your Mac in which an app asks permission to access your location, photos or contacts.
