iCloud Data Protection

iOS now has Advanced Data Protection for your devices and if you are concerned about security, then this is how you enable the feature. It's the best way moving forward to protect your information should it ever get into the wrong hands. 

Make note that you need to make a recovery contact or a recovery key to access your account in case of disaster. Once you set this up make sure to keep this information in a safe place.  Not doing so will lose access to your iCloud data.

Link