Headphone jack function as mic jack? (XPS 15)

Hello!

I have a new XPS15, running Windows 8.1, and a Realtec Hi Def Audio sound card.

There is no mic jack, but I'm wondering if there is a way to use the headset jack as a mic jack. I ask because if I plug in my mic, it does "hear" but at levels too soft to be useful.  When I plug anything in there, the Dell Audio asks me to identify it and includes the option to select microphone.

Thx!