Dunno what made me think of this just now. When I worked for IT in a school district way back in the 90s, a librarian told me she kept a supply of mouse balls in her desk because kids would steal them out of the school computers. What I remember about those balls was they picked up dust and crud off surfaces. Pretty soon optical mice came along and they were history.
I only did it once, because I hated the teacher and I guess I thought that would send a message. I was immediately caught and the kid who saw me pocket it kept saying I “liked mouse balls,” so it really backfired pretty spectacularly.