Advantage of getting a trap is you can deal with critters whenever they arrive. Placing a small dish with a bit of peanut butter is probably enough. Bad news is you then need to drive the unlucky rodent somewhere to release. Place a cloth over the cage to keep them calm, and wear gloves.

Your bigger issue is how are they getting in (like noted above). Soffit, or you have gaps somewhere where air only is expected in. If you get an energy audit, they will block off alot if not all of the gaps as part of an insulating job.

Good luck!