There is no way to determine if you have been caught speeding if you were not pulled over. However, if you were caught speeding by a traffic camera, you will be issued a ticket through the mail, typically within 30 days of the event.
Find Law cautions drivers not to give in to a traffic camera ticket, but instead to consider measures for arguing the citation. The Governors Highway Safety Association states that only 12 states have traffic cameras set up to issue citations for speeding. Being pulled over at the time of speeding or caught on camera in one of these states are generally the only two instances in which someone can be caught speeding.