How to catch the moment of creating order - both in frontend by client and in backend panel by user?

I want to catch the moment of creating order - both in frontend by
client and in administration panel by user. I’ve got a plugin for it:

class Plugin
{

public function afterSave(
    $subject,
    $order, $additional = []
)
{
    exit('aftersave');
}

public function afterPlace(
    $subject,
    $order, $additional = []
)
{
    $order_id = $order->getEntityId(); // this is null
    exit('afterPlace');
}

}

The afterSave method is not executed when creating order. The second -
afterPlace method is executed, but I cat’t get the entity id.

How to do it? What method should I listen to or how to get the order id?