If you tap Menu > Camera, the camera will be opened. If you take a photo, a waypoint will be created at your current location. The photo will be added to the waypoint and can be shown by opening the waypoint details screen.
The photo will also be saved in your photo library if you give Topo GPS access to selected photos of your photo library (iOS Settings > Topo GPS > Photos). The photo stored in Topo GPS is always a copy of the original. If you remove the photo in Topo GPS it will not be removed from your photo library. And also if you remove the photo from your photo library, it will not be removed from Topo GPS.
If you are recording a route you can include the waypoints with the photos in the route. If you save the recorded route make sure that the setting ‘Include waypoints’ is set to ‘Near route’. Then all waypoints with photos that are loaded on the map and are near the route will be included in the saved recorded route.