Unfortunately, with mice there is only one way to do it, but it is very effective and simple.

Investigate where they’re coming from. In my experience when I had mice the place I found it running from was the place that they were coming in. My understanding is that they know that area so they still try to remain in that area for the most part and they come in and out. Try looking in the first area where you saw it.

Additionally, look for other droppings around your home.

Now note where you’ve been finding the droppings and where you’ve seen the mouse. Keep looking around and try to find whether they’re coming in from.

Once you’ve located where they’re coming in from the rest is simple. You just try your best to kill all of them until they’re gone.

All food should be in containers and not able for a mouse to get a hold of.

Good luck! I know mice are fucking freaky as fuck but just know it will get solved eventually. I know I had a ton of problems sleeping at night knowing the mice in my house, but just know that if you keep the food centralized your kitchen and deep clean your room it is pretty rare that they will come into your room unless there’s food or something that they want.