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A Time Capsule can only be used to make backups of a PC or a Mac with Time Machine, or to store files manually. You can only make backups of your iPhone onto iCloud or iTunes.
If you make backups in both places, your Camera Roll photos are backed up automatically and, if you are using a Mac, you can transfer them to your computer
The iPhone cannot backup directly to the Time Capsule, if that is your question.
The iPhone backs up to iTunes on your computer or to iCloud.
If you have your Mac set to back up to the Time Capsule, then the iPhone backups in iTunes will be backed up.
More info on iOS backups is here: