Michael J. Swart has an Extended Event and a query to help monitor deadlocks:
Guess what? Apparently I “reinvented the wheel”. The extended events session I created is equivalent to one that Jeremiah Peschka wrote two years ago in Finding Blocked Processes and Deadlocks using SQL Server Extended Events. The embarrassing thing is that in Jeremiah’s article, he references a tool I wrote. And the first comment was written by yours truly.
There are a bunch of ways to capture deadlock information. This is a good one.