Access the state and country picklist through Apex

• For Lightning UI : "Setup | Data | State and Country/Territory Picklists | Complete all the steps" 
• For Classic: "Setup | Data Management | State and Country/Territory Picklists | Complete all the steps "
• Find below the link that has steps to enable the state and country pick list in the ORG. 

Schema.DescribeFieldResult fieldResult = User.Countrycode.getDescribe();
List<Schema.PicklistEntry> ple = fieldResult.getPicklistValues();
System.debug('Picklist::'+ple);
for( Schema.PicklistEntry f : ple){
System.debug(f.getLabel() +'::'+ f.getValue());
}

Schema.DescribeFieldResult fieldResult = User.statecode.getDescribe();
List<Schema.PicklistEntry> ple = fieldResult.getPicklistValues();
System.debug('Picklist::'+ple);
for( Schema.PicklistEntry f : ple){
System.debug(f.getLabel() +'::'+ f.getValue());
}