How to trigger a Webhook when an Approval Level is Approved?

How to trigger a Webhook when an Approval Level is Approved?

I would like to trigger a webhook when an approval level is completed What's the best way to achieve this?

In Custom Triggers a Webhook is available as an option to:
  1. Request
  2. Problem
  3. Change
  4. Release
  5. Project
  6. Task

BUT not on:
  1. Note
  2. Notification
  3. Approval Level
  4. Approval
I don't want to use a Custom function (and that a webhook) I want to use the Webhook feature.