I would believe him by default, especially if there was a possible credible cause or motive (e.g. your friend is a dissident in some less democratic country). T

I would believe him by default, especially if there was a possible credible cause or motive (e.g. your friend is a dissident in some less democratic country). The alarm clock seems harmless, mine has done that in the past due to faulty switches. As for things in the room, I'd advice him or her to use reliable and consistent tests to confirm or disconfirm the hypothesis, for example by making pictures of the apartment, noting the position of objects in the apartment and keeping the notes with you, installing a camera at the entrance, etc. The East German Stasi did things like that to a few select regime critiques. For example: rearranging or removing towels, replacing freshly bought milk with spoiled one, making medical doctors give you the wrong medication. These incredibly evil practices were called Zersetzungsmaßnahmen and only used on a few hundred to thousands dissidents at maximum.