x-select-enable-clipboard

x-select-enable-clipboard is a variable defined in `select.el'.
Its value is

t

• This variable is an alias for `select-enable-clipboard'.
• This variable is obsolete since 25.1;
  use `select-enable-clipboard' instead.

Documentation:
Non-nil means cutting and pasting uses the clipboard.
This can be in addition to, but in preference to, the primary selection,
if applicable (i.e. under X11).

You can customize this variable.