The Physics Constraint has a “LinearMotor” category that contains a Position Drive (spring) and a Velocity Drive (damper). The easiest way to make a spring is by enabling the Linear Position Drive and setting the “Linear Position Strength” to the spring constant you want. You also need to set the set the proper axis (XMotion/YMotion/ZMotion) to “free”.
This example makes a spring-damper in the Z-axis of the constraint component.
