From questions to ask a ScrumMaster in the interview to…questions you should be asking…THEM!
Savvy has an interviewing article here - https://www.linkedin.com/pulse/savvy-360o-how-interview-scrummaster-savvy-katham
And here’s a list from the Scrum Alliance - https://www.scrumalliance.org/agilecareers/careersblog/february-2016-(1)/38-scrum-master-interview-questions
Another from the Scrum Alliance for what Hiring Managers should look for - https://www.scrumalliance.org/agilecareers/careersblog/june-2016/what-do-you-look-for-in-a-servant-leader-or-a-scru