When you are Migrating your SharePoint site from 2010 to 2013, you need to make sure that event receivers attached to any list should be not be missed out. So to check the list of Event Receivers attached to a custom List.
Power Shell command to get the list of Event Receivers are as follows:
$spWeb = Get-SPWeb Identity http://mySite
$spList = $spWeb.Lists[["Custom List"]
$spList.EventReceivers | Select Name, Assembly, Type