Can you use your iPhone as a security camera?

Salutations mizzo118, 

The following article goes over the options for accessories that can be set up in the Home app. Just click on the Cameras option at the top if the link doesn’t take you there automatically - Home app - Accessories

Here’s more on how to set up security cameras in the Home app - Set up security cameras in Home on iPhone

With any HomeKit-compatible camera, you can view video streams in the Home app, choose who can view those streams, and set up notifications when activity is detected.

If you have one or more HomeKit Secure Video cameras, you can additionally take advantage of these features:

• Encrypted video: Video captured by your cameras is privately analyzed and encrypted on your home hub device (HomePod, Apple TV, or iPad) and securely uploaded to iCloud so that only you and those you share it with can view it.

• Record video: If you subscribe to iCloud+, you can view the last 10 days of activity from one to an unlimited number of cameras. The 50 GB iCloud+ plan supports a single camera, the 200 GB iCloud+ plan supports up to five cameras, and the 2 TB iCloud+ plan supports an unlimited number of cameras.

Note: Video content doesn’t count against your iCloud storage limit.

• Activity Zones: Create zones that focus your camera on the most important areas within its view.

• Face recognition: Receive notifications when people you’ve tagged in the Photos app are within the camera’s view.

Thanks. 

No. You can use it to monitor security cameras.