MacBook cannt connect to iPhone by bluetooth

Bluetooth pairing an iPhone or iPad and a Mac is not supported. 

If you are attempting to use Handoff/Continuity or AirDrop, that does involve Bluetooth but the devices are NOT paired; Bluetooth just needs to be on and the devices in range of each other. The following may help with Handoff/Continuity issues: Use Continuity to connect your Mac, iPhone, iPad, and Apple Watch - Apple Support

Also see Share files between your Mac and Bluetooth devices - Apple Support

And see the information in: Bluetooth: Why can't I pair my iPhone or … - Apple Community

Macs and iPhones don't use Bluetooth pairing with each other.

They typically work together using some combination of

• iCloud synchronization,
• Other cloud-based synchronization (e.g., connect both to the same IMAP e-mail account),
• Continuity features,
• Subscription to common services (e.g., Apple Music; Apple Arcade; Apple TV+), and/or
• Finder/iTunes-based synchronization (e.g., for loading music from your own CDs onto the iPhone)