At least a few years ago, I read a suspense novel which depicted a stalker watching his victim online. He had infected her home computer with spyware, and whenever she walked in front of the webcam he could see her. I don’t recall the book’s title or author, but if memory serves, he enjoyed watching her do stretching exercises while naked.
I took heed. A piece of paper is taped over my laptop webcam, which as far as I know doesn’t harm the lens. No adhesive touches the lens, and it’s removed easily when I need to use the webcam.
Here’s a link to an article in The Guardian, explaining why this might be a good practice. If you have any questions about which materials are best for this purpose, speak to a technician.