How do I simultaneously record through a usb mic, and play through the headphone jack? Can I do this with Garage Band?

Hi

I need to be able to record my voice through headphones with a mic, and play simultaneously back through client headphones via the jack (I am a hypnotherapist and hearing a voice inside your head via headphones is very effective).

I have Garage Band and I also have Audacity but can't work out how to do this on either.

Any suggestions gratefully received!

Many thanks

Leonie