Hi mshrestha42,
Thanks for reaching out to Apple Support Communities. It sounds like you're having an issue with the Universal Clipboard feature. We're happy to help.
We recommend ensuring your MacBook meets the hardware requirements found in the "Universal Clipboard" section from the article here: System requirements for Continuity on Mac, iPhone, iPad, iPod touch, and Apple Watch
If so, we'd recommend a normal restart of both your Mac and iPhone as well as reset of your Wi-Fi router or modem. If needed, the articles below will help:
Log out, sleep, wake, restart, or shut down your Mac
Restart your iPhone
If the issue continues toggle Handoff off, and back on again for both your Mac and iPhone: Continuity: Use Handoff to continue tasks on your other devices
If the issue remains, forget the Wi-Fi network on both devices and reconnect to test. You'll want to test with multiple native Apple apps, and starting from the Mac to the iPhone and then from the iPhone to your Mac.
Next, test in a new user account. If needed the guide here will help you set that up: Set up users, guests, and groups on Mac
Should you continue to have issues with the feature, reach out to Apple Support. You can get connected using the links below.
Contact Apple Support
Contact Apple for support and service
Cheers!