How to retrieve the mount passphrase of encrypted home folder of a user

Login as the user whose passphrase you want to see. Enter the following command in a terminal window:
$ sudo ecryptfs-unwrap-passphrase ~/.ecryptfs/wrapped-passphrase <enter>

Enter the user’s login password when asked.
You will be see a long string of digits & numbers (hexadecimal). That is the passphrase.

Record it in a safe place for future retrival of data from the home folder if you need to do so.