You need to backup the data from your account or the account of another employee? There are several possible methods.
The easiest one is to use Google Takeout backup services, which allows to backup the user data at once or only specific services of your choice. In the case of using this service for the emails backup, you should remember that all emails are backed up in mbox format that you can open eg. via Thunderbird mail client.
If you want to backup the emails/ contacts/ calendar to the Outlook, use an add on GASMO that sets up itself after the installing. If you plan to backup a larger mailbox, keep in the mind to increase the size of the pst file. If you plan in the future to migrate this backed up emails into the employee email box, your preferences should be to backup it as pst file. The PST file can be easily migrated by using a migration tool. MBOX format not.
In the case of an above menti-oned free applications and services, there is not a simple way to backup data of an employee if he/she doesn’t know the password of the other employee account. The exception is Gmail application, the is a possibility to backup the emails of every employee by the GAM tool. You can read more about this tool in the following article.
There are also payed tools that enable an automatic data backup of all users several times a day. In regard of paid tools we can recommend primarily the backupify service.