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

https://daltonnzom925.talesignal.com/posts/signs-you-have-mice-in-your-crawl-space-3

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