Capture information about Apex callouts that use named credentials as their endpoints with the EventLogFile object’s new Named Credential event type. This event type is ideal for auditing the installed managed packages that use named credentials.
Where: This change applies to Enterprise, Performance, Unlimited, and Developer editions. This event is available in the API but not in the Event Monitoring Analytics app.
Get Information About Named Credentials in the EventLogFile (salesforce.com)