Is there a way to back up agent jobs?

SQL agent jobs are stored in the system msdb database, so backing up that database will do what you need.

In a disaster, you can restore the entire msdb database, or, if necessary, recover individual jobs from a restored copy of msdb:

Serverfault: Recovering a specific job definition from an MSDB backup?

If you want them in a more immediately usable format, you can right-click and script out individual jobs manually, or if you'd like to script out all jobs on the server at once:

Stack Overflow: Automatically create scripts for all SQL Server Jobs

Another way is to just export to file using dbatools

Get-DbaAgentJob -SqlInstance workstation\sql2016 |  Export-DbaScript

you can even script out your entire instance or subset including agent jobs, operators, logins, etc for disaster recovery purpose.

Edit: Above will have the flexibility to filter out jobs that you do not need. Backup / restore of msdb is all jobs.. just FYI.