I hadn't thought of a hardware keylogger, but incidentally I have a lock in my PC case and the USB ports are visible. Do you know in what kinds of ports you could plug an off-the-shelf one?

No idea. The whole idea is that I shouldn't need to know much about physical data security on the principle that untrusted people can't physically access my machines.

House cleaners are probably the antithesis of tech oriented people unless they do the cleaning for the specific purpose of cyber-theft

I'm thinking of an organized crime operation that uses the house cleaners for easy access to people's homes and a ready-made hardware attack designed by someone else that the house cleaner just operates by rote instruction.

Also, I'm assuming the standard stereotypes for menial workers being utterly technology illiterate apply much less to anyone under 30 who grew up in a country with ubiquitous IT.