make it possible to register webhook to API

Question

I'm fairly new to webhooks and need to make it possible to register a webhook to an API that I'm creating. I use schemas to create and store data. I want the webhook to emit an event whenever a new 'student' object is created from the schema. I want the user to able to send a webhook request to https://localhost:8080/api/webhook containing a hook-secret in the header and along with the URL, to which the emit event will be sent, in the body. If I create an object from, say a 'subscriber'-schema for each webhook, how should I go about emitting the event to all webhooks?

I'm writing in Vanilla JS. I'm using Express and Socket.io for the server. MongoDB as database.

Can I use res.io.emit() to do it? If so, how do I tell the function where to send the emit event?

This is how I currently register a subscriber/webhook:

export class WebHook {
  authorize (req, res, next) {
    if (req.headers['x-app-secret'] !== process.env.HOOK_SECRET) {
      res.status(403).send('incorrect hook secret')
      return
    }
    next()
  }

  async registerSubscriber (req, res, next) {
    try {
      // Creates a new subscriber object.
      const subscriber = await Subscriber.insert(req.body, req.user).then(response => {
        return response
      })

      res.status(200).end()
    } catch (error) {
      let err = error
      err = createError(500)
      err.innerException = error
      next(error)
    }
  }
}

An this is the function for how a new student object is created, and where I want all the subscribers to be notified:

 async create (req, res, next) {
    try {
      // Creates a new student object.
      const student = await Student.insert(req.body).then(response => {
        return response
      })

      // SOMETHING LIKE "res.io.emit()" SHOULD HAPPEN HERE:

      res
        .status(201)
        .send('Accepted')
        .json(student)
    } catch (error) {
      let err = error
      err = createError(500)
      err.innerException = error
      next(error)
    }
  }