Laravel nova：如何定义belongsTo选项值

Right now by setting up belongsTo relation in laravel nova resource I am getting option values as ID's, but instead I need plan_service_id and I am not sure how to achieve this... Code:

Nova TeamSubscriptionResource:

public function fields(Request $request)
    {
        return [
            BelongsTo::make('Plan', 'plan', 'App\Nova\Plan')->display('name'),
        ];
    }

Plan model:

public function teamSubscriptions()
    {   
        return $this->hasMany('App\TeamSubscription', 'stripe_plan', 'plan_service_id');
    }

TeamSubscription model:

public function plan() 
    {
        return $this->belongsTo('App\Plan', 'stripe_plan', 'plan_service_id');
    }
}

Current result option value is filled with $plan->id:

current html result

Result wanted, option value should be filled with $plan->plan_service_id:

wanted html result