Mice in a crawl space may reveal themselves through scratching sounds at night, droppings, chewed openings

https://rylanhuou497.theglensecret.com/what-to-do-if-you-hear-scratching-in-your-ceiling-1

Mice in a crawl space may reveal themselves through scratching sounds at night, droppings, chewed openings, nesting material, or even unusual pet attention.