Need to capture the logs for changes made in the workflow

We have requirements to capture logs to monitor the changes made in the  workflow of project customization

.i.e. Need to capture user name  &  workflows function name that has been updated on date. 

My understanding is these will not be captured as part of  audit  logs.

Can you pls help me if anyone has  already implemented the same in workflows .

Is there a way we can capture logs from site admin or if we can develop some kind of custom tools where we can capture these logs from application server/site admin/project customization. 

Your inputs or providing any kind of help  will be much appreciated!!!