Mechanical Engineering Small Job

I am looking for help making a simple spring-based mechanism: a compression spring that is attached to a string that when the string is pulled the spring uncoils outward and when I use my hand to push in the spring, or some weight, the spring re-coils. Every time I pull the string I want the spring to boing outward, and every time I put some pressure on the spring i want it to recoil in.