To scan a document with an iPhone, you can use the built-in Notes app, which has a native scanning feature. Here's a step-by-step guide:

1. Open the Notes app on your iPhone.
2. Tap the New Note button to start a new note or open an existing note.
3. Tap the Camera icon or the paperclip icon (depending on your iOS version).
4. Select Scan Documents.
5. Position your document so it appears fully in the camera view. The scanner will automatically capture the image of the document. You can also manually capture the scan by tapping the shutter button or using the volume buttons.
6. Adjust the corners of the scan to fit the document if needed, then tap Keep Scan.
7. You can scan multiple pages by repeating the above steps and adding more scans.
8. When you're done, tap Save to add the scanned document to your note.
9. You can share the scanned document by tapping on it and using the Share button to send it via email, messages, or save it to files as a PDF.

This process works on all iPhones running iOS 18 or later and does not require any third-party apps. The scanning feature can also work in the Files app with a similar process. This method is simple and helpful for digitizing receipts, forms, paperwork, or any physical documents directly on your iPhone.