如何收到我通过PayPal发送付款的IPN通知 - Ruby on Rails

I have an option on my website to allow the admin to send payment to users through PayPal, how can I make sure that the funds have left the admin's account? Is there an IPN notification for this? I am trying to update a field in my database to true once the payment has gone through. I have an option on my website to allow the adm