Look for “Closest points between objects” in the first post in this topic: ClosestPt2Objects.py (3.7 KB)
Also, in post #15 there is a plug-in called “byRhinoGadget”, which contains a few similar tools, such like “Distance between 2 faces”, “Distance pt between 2 objects”, “Farthest 2 points in a curve”, “Min Max distance from 2 curves”…