Moving a small pin up and down using <12v
For higher speed output, you'll need solenoids. These are readily available commercially. You'll need to specify length of stroke, holding force, and push or pull, among other things. You are also probably going to need an alternate source of power and a relay setup to control them adequately.

For slower speeds, a servo mechanism may be best - simply attach the pin to a small gear with a pivoting arm such that a 180 degree causes the desired extension. I say simply - this could actually be pretty difficult to do with simple hand tools. 

Depending on the specific application, you may also want to look at other electromechanical or mechanical options, such as pneumatics, or even hydraulics - everything depends on the application.