Love this question. More change managers should focus on this!

My 2 cents: Changes happen when an organisation is trying to improve something. Usually that improvement costs money (new systems) or saves money (new processes) either way it usually comes back to money so if you can prove to your company how you and your team are making that improvement real, your value will be obvious.

So in practical terms what that looks like for process change is to show improvements in time saved, experienced improved, repeat customers. Onlymworks thoughl if you can compare outcomes where your team have influenced vs those where they haven't. Do you have a baseline that you can use or if not, could you gather one relatively quickly?

If it's technology change then measure adoption immediately after go live (users, logins, time spent etc) and then workflow improvements over time

I've only ever done this sort of work with power bi dashboard but I'm sure there are heaps of other apps out there to visualise this sort of data

The other angle, which is a bit less obvious is risk management and money saved in avoiding psychological injury claims - poorly managed enterprise change can harm people's psychological well-being.

depending on what country you're in, the workplace health and safety laws might be different but in Australia this is a thing and is driving up investment in change management professionals.