It can be done, but the tenor of your question makes me think it's a bit beyond your scope unless you're willing to read up on what is required.
If the two wires going into the box are both black, both blue or both red, then you would need to pull at least one wire, preferably two.
Switches interrupt the power to fixtures by breaking the hot line of the circuit. You don't have to have both the hot and neutral going through the box, though they often do since they're both coming from and going to the same place. The neutral simply goes past the switch without being affected by it.
But occasionally, as here, only the hot goes through the box. If you want to add an outlet, you'll need to add the neutral and preferably a ground. Without those, an outlet is just a bit of abstract art.
I won't go into the in-depth instructions of how to go about that. Either you can do it, or you can research the topic and figure out how to do it, or you can't - in which case you need an electrician.
Good luck with it.