We use a Cinnado brand indoor security camera for in the house. Mains powered. They were cheap off Amazon and appear to work well. Link to a free app for notifications that you can 'arm or disarm' as required. The notifications send an alert to a phone of your choice, and footage to view. There is more functionality with the subscription service, but we don't use that. The free one gives us enough to be notified of a movement, footage to review to decide whether to get on the phone to plod as there's an intruder, or whether, as has happened recently, it was triggered by a spider crawling over the camera unit

We've been happy enough to buy a couple more for in the garage and shed. The free app will manage a small network of cameras rather than needing a separate account for each camera.