Can I lock a bone to another object's location?

I have modelled a cable, with a connector at each end. The ‘cable’ is made using a tubular mesh with an armature down the centre to define its shape. The ‘connectors’ are just cubes for now. I want to be able to move one of the connector objects, with the end of the cable staying stuck to the connector.
So, in Pose mode, I have selected the end bone of the armature and given it a Location Constraint, specifying the name of the connector (i.e. the cube) as the target. However, when I animate the position of the cube, the end bone of the armature makes no attempt to follow the position of the connector.
Firstly, is it possible for a single bone in an armature to follow another external object? If so, what am I doing wrong? I have practised making other simple objects follow others using a location constraint and it has always worked perfectly, but not for an armature bone…

How about an IK Solver for the bone which is actually the cube?

Many thanks - that’s done it! And it works for both ends of the cable, so even better. A day just isn’t complete unless I learn something new in Blender.