Laravel 5.4 : Many to many pivot table records

I have User and Project models.

The relationship is mant to many.

public function projects()
{
    return $this->belongsToMany('App\Project')->withPivot('id');;
}

And in Project i have :

public function users()
{
    return $this->belongsToMany('App\User')->withPivot('id');;
}

Now what i am doing :

$projectsAsFreelancer = App\Project::where('assignedTo',$id)->get();

What i want is to get the username from the users table of the user, Who have posted the project. The Project means projects table have the forign_key->employeer_id.

Currently $project->pivot->username gives me error.

pivot table name is project_user.

What i am missing ?

via Chebli Mohamed