Determine unique builds

In our project, there are cases when code changes are made on the fly and deployed over the devices. This is made by multiple developers.

We have a requirement where we need to generate a unique hashcode for a specific set of code when build is created. So for eg initially the hash code is "abcd".

I changed code in a CS file Employee.cs and updated a method. Once I compile the hash code should change to something else e.g "defg".

If I revert my changes, it should revert to "abcd".

Is this possible to do? I am using C#.