There are so many things that would have to go wrong for a third party app to surreptitiously activate your camera and pick up images in the background on iOS, this is tin foil hat level concern.

It’s also hilarious how many people worry about covering up their camera on the laptop not thinking that the microphone can pick up much more information in the surrounding area - again worrying about the wrong thing.

Also see, not using biometric security because in the US, police can’t legally make you give up your password - even though police are not above rubber hose decryption, judges hold people in contempt indefinitely and iPhone and Android phones are laughable insecure after first unlock after rebooting your phone.