Backup of data on iCloud
For complete belt &amp; braces, you really need a minimum of 3 distinct locations for any data you consider 'permanent'.


Your computer.
a local backup  
an off-site backup.


There can be some element of redundancy in this.  

You can backup your iPhone to your computer, via iTunes.  

Your computer then ought to be backed up to either another computer in the same building, or to a hard drive, connected especially for that purpose. For Mac, Time Machine is the perfect solution. For Windows, something like Acronis. 
This ought to be good enough right up to the point the house burns down ;)

To be secure even in that remote eventuality, your computer, already containing your safety backup of your iCloud/iPhone data, can then separately be backed up to another online service such as Backblaze. Acronis also have a cloud solution - I've not tried this myself, but it may be worth investigating.