Back up entire computer to the Cloud

Apple offers iCloud Backup for iPhones and iPads but not for Mac computers.

It is possible to sync data from a Mac to iCloud if you turn on those options (e.g., iCloud Photos, iCloud Drive including the Desktop & Documents option). Syncing has some of the benefits of a backup (and the benefit of being offsite) but is not the same as a backup. Major differences include the fact that not everything on your Mac can be synced and the fact that if you delete something, accidentally or otherwise, there is only a limited time period (30 days in most cases) during which it can be recovered.

Also see: https://support.apple.com/mac-backup

And more information on syncing in:

Set up and use iCloud Photos - Apple Support

and

iCloud Drive FAQ - Apple Support

Also, Time Machine does backup photos. If yours are not backed up, the following may help from Back up your Mac with Time Machine - Apple Support

• To exclude items from your backup, open Time Machine preferences, click Options, then click the add (+) button to add an item to be excluded. To stop excluding an item, such as an external hard drive, select the item and click the remove (–) button.