To Get the message in your mobile number follow below steps:-

Message methods from https://graph.facebook.com REST API.

They include /{Version}/{PhoneNumberId}/messages for sending messages.

To get your own credentials-

First register as a Facebook developer - https://developers.facebook.com/docs/development/register

Second Create your App - https://developers.facebook.com/docs/development/create-an-app

To send and receive a first message using a test number, complete the following steps:

1. Set up developer assets and platform access
2. Send a test message
3. Configure a Webhook
4. Receive a test message