Oomis is absolutely right – rodents don’t keep secrets. If a mouse is happy in your house, he will soon bring his friends and family. Which is why you want to get rid of it as soon as possible.
My advice (if you are not squeamish) is to try and figure out where the mouse likes to go at night (when he gets hungry and no one is around) and hunt him yourself. It might not be so easy to figure out. You can get old fashioned spring loaded snap traps (the kind that slapstick artists and cartoon characters were always setting off on their fingers) for under $1 each.
Put some bait on the trigger – but don’t bother with cheese. In my experience, they don’t seem to be as interested in cheese as we are made to think. (Could be that they don’t like the processed stuff, but if you had aged cheese it would be different). No matter – they love sugary cereals. Put a piece on the trigger – and tape it down! Otherwise, the crafty guys will take it without setting the trap off.
I know some people don’t like using these traps, because the mouse is killed, but its quick. And it works. I hope it works for you fast!