That looks like a job for a scanner, since the wall might not move as a unit and you don't know how many reference points you need. You might need to set some nails in there for future horiz/vertical alignment of the images.
Start with a robust control baseline/network so you can prove your control is not moving. Then move to collecting data on the wall. A baseline with 3 points on line between the 2 end points and then a couple of angle checks for example. Steeples or antenna towers work well. Targets affixed or otherwise physically a part of the wall allow for the repeated measurements. Do you measure every stone with a scanner or do you identify individual points of interest? The more you can keep everything the same (equipment, procedures, observation points) the better.
Bill and Lurker have some great ideas. I’m curious as to the reason for this? What’s the time frame? Be sure to budget accordingly 💲
Scan it. Software will show differences between scans.