When I try to hit the mole the hammer keep hitting the same spot no matter where I put the mouse.
The hammer will hit a pre-determined spot if you do not click on a specific prairie dog.
You'll notice that the hammer cursor has a white circle which represents its hotspot. You just need to make sure you're clicking the white circle part of the hammer on the prairie dog that you want to hit.
Thanks worked perfect I actually finiished the game last night.