Calling Queueable Interface from Trigger/Class/Controller in Salesforce.

To call a Queueable class from you Trigger/Class/Controller simply place use "System.enqueueJob(new ClassName())".
Example:-
trigger AccountTrigger on Account (before insert) {
if(Trigger.isBefore){
if(Trigger.isInsert){
System.enqueueJob(new QueueableExample(Trigger.New));
}
}
}