I was only able to get this far with adding automation to the field, to post a new value to the chatter with:

records.message_post(body="Value changed to: " + record.***technical.name.of.your.field***)

as suggested by Swasti, you can create a new field and store the previous value there (or all values that ever occurred in the field). 

I had this done with automation, and added a field in studio named x_studio_name_changes. 

The code for automation:

# check if the "changes" field is empty - you can try to capture this with different method but this one worked for me fine.

if record.x_studio_name_changes == 0:
  record['x_studio_name_changes'] = ""

# add the new 'name' to the end of "changes" field after '; ' sign (if it's not empty which we checked before)

record['x_studio_name_changes'] = record.x_studio_name_changes + "; "+record.name

# put a note into logger with info that 'name' was changed

records.message_post(body="Name changed to: " + record.name)

hope this helps :)

I'm not yet fully familiar with the direct coding inside the source codes so try to work around with studio and some automatons :)