image processing – Extract data from picture of experimental instrument

I need to transform many pictures of an analog clock with only on pointer ( the one of hours ) in the corresponding numerical data.
Is it possibile to do it with mathematica? I would like to find some documentation about this.
Thanks in advance

You suggest to give an sample image (is not a clock is a dynamometer but is the same problem, I talk about clock to simplify)
About the code I have no idea how to do it, this is why I am asking documentation. Sorry.
enter image description here