Answer:
There are chemical repellents out there to deter mice, but a simple natural way to do it is with peppermint. They do not like the smell of it.
Soak some cotton balls with peppermint oil and put them where the mice were seen moving around. Peppermint leaves may also be spread around to drive off the mice.
Smell of ammonia also keeps mice away. Keep children away from ammonia when you use it.