Hire a Rent-A-Cat. Preferably a girl cat. Boys don't hunt as much. That squirrel will leave in a hurry. Squirrels don't mind too much about a dog. But a cat is a different story.
When I was married, we owned a house next to a green belt filled with ground cover, a perfect place for all the field mice. The neighbors on both side were careful and never left the garage door open unattended. Yet they both had field mice move in and running up and down in the walls.
My house on the other, we regularly left the garage door open. We also had a kitty door from the utility room to the garage and the garage is where we kept the litter box. We never had any field mice inside the house except on rare occasions when my two wonderful kitties were proud to show me their catch, field mice, birds, and once a juvinile bunnyMice are not that dumb. They know where its safe and not. House with two kitties is definitly a no no no matter how easy it is for them to come into the house.
smilingcat