I had the same thing a few years back at my previous abode.
I saw one scampering across the floor and thought it was alright. A few weeks later there was more of them and they were taking liberties and I thought I need to act....
I got one of those high pitched thingies as didn't want to kill them and they did work.....
Unfortunately a week later my neighbour (young single parent female) knocked on to say she was moving out to her parents for a while as her house was infested with mice and did I have a problem
I played the innocent and said no. She had called out environmental health and i did the same too. I didn't like to do it but felt i had no choice. The rat man came and laid poison around the house. On two seperate days there was a small mouse on the kitchen floor dead......
So the sirens do work, but just shift the problem elsewhere.
Never had a problem after that.
thank f*** your not my neighbour