I have got this, to check, if you have voted or not

$post->voters->find(auth()->id())->exists(); //will return true or false

Now, if you are more willingly looking for is it up or down vote

$post->voters()->where('user_id', auth()->id())->where('type', 'up')->exists();

$post->voters()->where('user_id', auth()->id())->where('type', 'down')->exists();