Notes
This is only for the Linux TTY. Tested on Gentoo.
Vim auto-decompresses the .gz file used by the TTY to convert keycode into key,
so there's no need to gunzip, vim, and gzip.
Editing the map file
nvim /usr/share/keymaps/i386/qwerty/us.map.gz - this path may be
different for non-Gentoo distributions.
Now replace all "Caps_Lock" occurrences with "Escape".
There should be just one for keycode 58 near the bottom of the file.
That finishes editing. :x to write and exit vim.
Hot-reload current TTY
Now on reboot/creating a new TTY Caps Lock will behave like Escape.
However, to reload immediately, do loadkeys us.