Microphone to Headphone port

How do you turn your microphone port or line in, to a headphone port or line out port. For a while I would plug in headphones into the mic port and it would bring up a dialog saying I could change it to another headphone port but it never worked. Now it doesn't even pop up. I want this so when I go on long trips my girlfriend and I could watch a movie together using 2 pairs of headphones.
WIN 8.1

Hi Erics9971,​

Welcome to the forum

Very cheap solution just purchase a headphone splitter to be able to use two pairs from one jack.

Just for an example:

Belkin 3.5mm Headphone Splitter - White: Amazon.co.uk: Electronics



Loads of different types on the Internet, search for headphone Splitter.

hope this helps

Cheers,

Harry