How to verify that a certain commit has been transmitted to standby
Without opening the standby for read-only, you won't be able to identify specific changes to specific physical objects, instead you'll have to verify that a specific set of changes have been applied to the remote standby. Views including v$standby_apply_snapshot, v$archived_log, v$archive_gap, v$dataguard_stats, v$managed_standby are all ones that I use on a regular basis to verify standby apply health. 

Additionally, you can use the dgmgrl command line interface to show the status of your log apply on the standby.