I think you might be able to. I say that because iOS will let you access volumes shared by macOS (via SMB) and I think the Time Capsule can also share files via SMB. In iOS, open the Files app, tap the "Browse" tab at the bottom. Now in the upper-right corner there are three dots in a circle. Tap that and Connect to Server.
Put in your Time Capsule's network device name and tap Connect.
The next screen might be a problem, depending on whether you have a "storage password" set on the TC or not. If not, Guest should work. If you do, maybe you have to set up Accounts on the TC (it used to be possible, anyway) so you have a userid and password to enter, or maybe it will work with a blank userid and the storage password of the TC.
Anyway, it does work with drives shared by my various Macs, when I enter a valid username/password for an account on that Mac.
(I've got a TC but it currently has no drive installed, since it failed. I used it for many many years, though.)