why do people always advise to break everything (e.g. relationship, rental agreement) at once as soon as you have suspicions? Nothing is for sure yet as far as I understand. now, back to the question. if you only need to see if your landlord is doing smth on your pc, you can install like software that tracks down activity on pc, takes snapshots of what's seen on desktop at certain time and so on - also in hidden mode. if you want to have footage that shows that he is trespassing your territory without your consent (to me it's more of a proof) then yes, it must be surveillance software. since I have just written it in another section, I'll tell once more - I recommend xeoma but not because I gain smth from it, which I don't, it's just brand-new and I started using it a couple of days ago and I absolutely happy i've found it. Helps me A LOT. Never used it for snapshot option but it does offer the possibility so feel free to go and check it.