Camera shutter coming from somewhere that isn't my Iphone?

For the past month or so I've been hearing Iphone camera shutters while I'm sitting in my living room. I live alone and am not taking the photos in order to make that sound ( they usually seem muffled or far away ) Is there any house hold item that could make a similar sound? I'm kinda spooked

Build a bomb when you next hear it set the bomb to 15 seconds run outta the room and bam if someone's taking pics of you their hopefully dead. Alright to be serious if its someone surely their not that dumb to not turn their phones on silent mode

It would have to be mains powered to keep running for a whole month.

Have you scanned your phone for viruses and malware?

Does it happen when your phone is switched off?

Do you have a PC (Windows, Mac or Linux) with a webcam?

If you don't find any other answers, listen to the voices in your head to see if they can help.