Mice are great at avoiding traps, can be very intelligent, and their use of sound and smell is excellent.  In this regard, if you hire an exterminator, it should be done only if you are so deathly afraid of dealing with live mice, dead mice, and you cannot fight the fear of the mouse.  You are someone who will be screaming on the chair, when you see the mouse.  It is your most primal fear.

This should not be your excuse, as you are going to have to deal with caught mice, see them, as the exterminator will not be able to rid your home of the problem in one setting.  It will take many visits, and can be expensive.  The service is a premium, and should only be employed if you are liable to a business or other human inhabitants in your home.

That being said, one visit may really help.   You can learn a lot from these experts.  They are well informed on how smart mice are, have many stories of infestations, and can make you feel more secure in your path to finding the solution to a mouse free home.

Be prepared however, as they will use poison, and that poison has a blood anti clotting feature.  It is really a bad option, painful for your mouse population, and can kill your pets.  It can take days for death, and they will end up in your walls.  The smell will stay in your home for long periods of time.

Trapping is always the best solution, and there are humane and better ways to find the best mouse trap.