Your macOS version is too old, if you’re still running El Capitan OS X 10.11 as indicated by the footer here.
Sierra macOS 10.12 is required.
System requirements for Continuity on Mac, iPhone, iPad, iPod touch, and Apple Watch - Apple Support
If you want to discuss macOS upgrades, please post the MacBook Pro model year from 🍎 > About This Mac.
Sierra and High Sierra macOS 10.13 require a mid-2010 or newer MacBook Pro.
How to get old versions of macOS - Apple Support
Unlock your Mac with your Apple Watch - Apple Support
Have a complete and current backup before any macOS upgrade, if your Mac supports Sierra or (better) High Sierra (or newer), and you decide to upgrade.