In some rare cases, hackers actually have recorded people and then attempted to blackmail them. It is particularly easy if one has Adobe Flash installed, because the settings for devices with built-in camera (and microphone) can be switched to “ON” quite easily.
There is also malware that can activate the camera (and microphone), though I’ve not seen much about it lately.
Remember this one?
https://www.usnews.com/news/articles/2015/07/29/tape-your-webcam-horrifying-malware-broadcasts-you-to-the-world