backup iPhone without itunes

Plug in your iPhone to your Mac using the lightning/USB cable. Open Finder on your Mac and see if our phone appears in the left pane. If it does, depending on your settings, your Mac will perform a backup automatically or you can trigger a backup manually by clicking Back Up Now.

I would highly recommend doing a local encrypted backup for 2 reasons:

1. local backups are more extensive than iCloud's
2. encrypted backups also back up sensitive infos such as your passwords.

They won’t even get that far, it will want them to enter the passcode on the iPhone.

IF you have been backing up and syncing with your computer and trusted it then the method proposed by 6x6 will work. If you have not you will have no way to back up to your computer.

Excellent point. If this is the case, hopefully zinnia40 can receive the 2-factor authentication code on a 3rd device, e.g. a trusted iPad.

I'm surprised: the device that needs to be trusted is the Mac, not the iPhone, and thus the Mac should receive the prompt to enter the 2FA code. Am I missing something?