I have always used <Esc> for switching mode to Normal mode (from Insert mode).
Now I have a new macbook and I need to use <shift-Esc> to switch modes (also working with <Ctrl-[> )
How can I configure it to only ESC key?
I tried to use inoremap in .vimrc file to remap, but it does not work, probably I did not use it correctly.
inoremap <Esc> <Shift-Esc>
According to the documentation shown when executing the command :help :map-which-keys, in order to use the Shift key in a mapping, for example as <Shift-Esc> as you are trying to do, it must be specified as <S-...>.
So in your case, changing the <Shift-Esc> in your mapping to <S-Esc> should work as you intend.
Alternatively, mapping the <Esc> key to <C-[> instead of <S-Esc> should provide the same solution.