You could use the keyword "haptic actuator" for searching. Haptics includes both vibration motors and resonant actuators used for tactile feedback.

I guess waht you want is a solenoid. A solenoid pulls or pushes the actuator shaft in or out when you energize the solenoid coil. If the shaft is too thin you can put a rubber or plastic cap on it.

Keep your sharing like this. You have made a nice post and I really learned a lot from you. It will help me work out my new project.