Artisan Call output in Controller?

I have a complex Artisan Command that I wanna call in my Controller also. That works. Except that it return an Exitcode instead of output.

use Symfony\Component\Console\Output\BufferedOutput; # on top

public function foobar(Request $request)
{
    $this->validate($request, [
        'date' => 'required|date_format:Y-m-d',
    ]);

    $output = new BufferedOutput;

    $exitCode = Artisan::call('foo:bar', [
        'datum' => $request->get('date'),
    ], $output);
    return $exitCode; # returns 0;
    return dd($output->fetch()); # returns ""
}

I want the output of the command. How to do that? The last line of my Artisan command has a return on the last line that should be returned.. How?

$command = 'foo:bar';

$params = [
        'datum' => $request->get('date'),
];

Artisan::call($command, $params);
dd(Artisan::output());