detection of deplacement on image processing

I am on a project of displacement detection on a small iron bar with
marking where we  applies an effort for that I use an image processing under vision assistant and labwindowscvi 2017 (converting the vision assistant script into code c), after treatment I use caliper which calculates distance between points after displacement I recalculate the moving and I'm making the difference to have my move from where
1 i would like to know how i can get these distances as a table
to reuse them in my code c
2 is this method the right one or there are better algorithms thanks for your help