Is there any macro that could track changes in an Excel workbook without the
workbook being shared? I came across the following macro:

Dim nFile
nFile = FreeFile
Open "C:\MyLog.txt" For Append As #nFile
Print #nFile, "Workbook " & ThisWorkbook.Path & _
" opened by " & Environ("UserName") & _
" on " & Format(Now, "yyyy/mm/dd hh:mm:ss")
Close #nFile

which saves a list of when the file is accessed. But I've no idea how to
amend this to list any changes to the the workbook. In actual fact, it's
only one specific sheet that I need to track, however the nature of the file
won't allow me to share it.

Any help would be much appreciated.

Andrew.