Hi Centime,
It sounds as if you have Continuity turned on allowing your MacBook to receive phone calls made to your iPhone, among other things. To turn this off, follow the steps in this article -
Connect your iPhone, iPad, iPod touch, and Mac using Continuity - Apple Support
Specifically this section -
To turn off iPhone cellular calls on your iPad or iPod touch, go to Settings > FaceTime and turn off iPhone Cellular Calls.
On your Mac, open the FaceTime app and go to FaceTime > Preferences. Click Settings and deselect the iPhone Cellular Calls option.
Thanks for using Apple Support Communities.
Best,
Brett L