You need to create a soft body object (wire or cloth) and attach a constraint to it before you can use this tool. Typically you will have animated the new host object (e.g. the skin) prior to creating the soft body object (e.g. the fur). This tool is useful, for example, to simulate hair attached to a moving character.
Using Attach Constraint to Animation
Click the Attach Constraint to Animation tool on the Wires or Cloth tab.
Select the constraint to parent and press Enter to confirm your selection.
This example shows a polygonal sphere with primitive normals turned on. The sphere is given some animation, converted to a wire object, given constraint, and the constraints are attached to the animation. When the simulation plays, the "hair" moves with the sphere as it rotates.