How to turn the space bar to another ctrl key?

How to turn the space bar to another ctrl key? It will be dam useful especially for Emacs users and also useful for normal usage like for tab changing in Chrome or Gnome terminal.

You may try 2 tools in userspace:

Space2Ctrl: https://github.com/r0adrunner/Space2Ctrl

xcape: https://github.com/alols/xcape

Note that the limitation of these solutions: the space will not work as ordinary until it is released, and it may act as a modifier unintentionally if you type too fast.