Karabiner Elements is not available for Linux but there are some alternatives that runs on Linux with similar functionality. The best Linux alternative is Actiona, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 50 alternatives to Karabiner Elements and seven of them are available for Linux so hopefully you can find a suitable replacement. Other interesting Linux alternatives to Karabiner Elements are Repeat (Free, Open Source), Key Mapper (Free, Open Source), xcape (Free, Open Source) and xmodmap (Free, Open Source).
Actiona (formerly known as Actionaz) is a task automation tool. It allows you to create and execute action lists. You don't need to know any programming language to use it: its intuitive interface allows you to create action lists (scripts) using drag & drop.
Repeate is a full-fledged, Java mouse/keyboard record/replay and automation hotkeys/macros creation using modern programming languages, and more advanced automation features. Working across three major OSes: Windows, OSX, and Linux.
The xmodmap program is used to edit and display the keyboard modifier map and keymap table that are used by client applications to convert event keycodes into keysyms. It is a part of the X.Org project.