Route::post('/user', 'UserController@get');

function get(Request $request)
{
    dd($request->input('Name Surname')); //display null
    dd($request->all()); //I notice the key's changed to Name_Surname

}

$data = $request->all()->mapWithKeys(function($item, $key) {
    return [str_replace("_", " ", $key) => $item];
});