You can trigger a ADO pipeline when a PR is created in bitbucket:
1- Create a webhook in bitbucket; set a pipeline trigger e.g. When a Pull Request is created. Specify a secret (optional)
2- Create a ‘incoming webhook Service Connection’ in ADO. Mention same webhook name as created in #1. Optionally, specify the same secret as in #1.
3- Add following resources parameters in the ADO pipeline (yaml file) that should be triggered when a PR is created in bitbucket repo where webhook was created in #1.
4- Optionally, you can bring in any variables from bitbucket (refer to ‘request’ payload of webhook in bitbucket) into ADO. Use following format:

Reference:
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