From DashExamples.com there's a quick post on how you can set up your application to notify you on content security policy violations and store them back on he server side for later review.

When somebody violates your CSP rules, there is a great feature that can setup for supporting browsers to send back the violations to your server to be saved, processed or whatever. This is a great feature because you can stop a possibly malicious piece of code from executing and learn which scripts may have vulnerabilities in your code.

The reports as delivered by the browser back to your server according to your site's policy setup. They're sent back as a JSON string that is easily parsed and stored. The post shows you a sample database table structure (storing things like request, headers, blocked location and IP address) and the PHP to handle the incoming post. For more about the CSP reports, see Mozilla's example on their Developer section.