A general approach towards installing Linux on Macs
First you need to shrink your main MacOS partitions from within MacOS, using ‘disk utility’ to make some space available for Linux.
Then, you need to boot the machine from a prepared Linux USB drive by holding down the option key upon starting up until boot menu appears.
After sucessful installation there remains the main task to keep the Macbook/iMac from overheating, but it can be done, once you learn how. ‘Mbpfan’ is the best tool for that, which I keep using.
Edit: Also see this article on t2linux, To-Linux-On-Mac-Or-How:
https://wiki.t2linux.org/roadmap/
…
Adding the following links as bookmarks for further reference:
- Current state of Mac on Linux (2016-17 models) (outdated)
- Which version is your Macbook Pro?
- Tutorial: Installing Arch Linux on a Macbook Pro 11,3.
- Mac on the Arch-Wiki (partially outdated).
T2Linux for Mac models with the Apple T2 Security Chip (2018-2020):
Dedicated pages on the Arch-Wiki for these models:
If all goes wrong: