Apple sidecar was introduced in MacOS Catalina (2019)

[chrisNova777]

https://setapp.com/how-to/how-to-use-apple-sidecar?ci=16155611168&adgroupid=164030912367&adpos=&ck=sidecar%20mac&targetid=kwd-692989069874&match=e&gnetwork=g&creative=694891009626&placement=&placecat=&accname=setapp&extensionid=&gad_source=1&gclid=Cj0KCQjwlvW2BhDyARIsADnIe-KPjC7d2KTLAzTlCMc41tXmlf2K9Dj8_m-Uph5qOsqr3afMMsU5aewaAuZdEALw_wcB

https://www.macrumors.com/guide/sidecar/

Sidecar Compatibility

Sidecar is limited to many newer Macs, and it is compatible with the following machines:

    Late 2015 27" iMac or newer
    Mid 2016 MacBook Pro or newer
    Late 2018 Mac mini or newer
    Late 2018 MacBook Air or newer
    Early 2016 MacBook or newer
    2019 Mac Pro
    2017 ‌iMac‌ Pro

Most older machines are blacklisted from taking advantage of Sidecar, but some older Macs can use the feature via a Terminal command provided by developer Steve Troughton-Smith. There are few details on this method, but those interested can check out our original article on compatibility.

On the ‌iPad‌, Sidecar is limited to ‌iPad‌ models that work with the ‌Apple Pencil‌, so older models that do not have ‌Apple Pencil‌ support can't be used with Catalina. Compatible iPads include the following:

    iPad Pro: all models
    ‌iPad‌ (6th generation) or later
    iPad mini (5th generation)
    iPad Air (3rd & 4th generation)