What does it look like, by chance?
If you do not wish to kill the mouse then a no-kill trap would be recommended. You can either buy one or make one yourself (I have included links at the end of this message for either case.) The only issue with the DIY mouse traps is that they can cause broken legs in the mice, so a store bought trap would probably be preferred.http://www.instructables.com/id/Simple--No-Kill--Mouse-Trap/http://www.uline.com/Product/Detail/H-4003...3w&gclsrc=aw.dshttp://www.scruggsfarm.com/victor-live-mou...CFeHm7Aod03gAWQ
Is there no way you could try ushering it into a cardboard box? Whenever my cat brings one in, getting it into the corner and then tapping the floor near it so it runs into the box always seems to work.