How can I access variables inside the function from outside in angularjs

anything within {...} that is declared (var, let, const) is inaccessible outside the {..}.

This is called scope. Read up on it. It is very important!
Everything you wanted to know about JavaScript scope[^]

In order to access it outside the scope, you must either declare it outside, or extend an object that has been declared outside (such as scope for example, but this is generally bad practice).

Declare outside scope:

var   lastlockerbalance = null; //declared in outer scope so in available in outer & inner scope.
var getlockerbalance=function(){
	$http.get("php/selectLOCKERBALANCE.php")
	    .success(function(lockerbalance){
	        $scope.lockerbalance1=lockerbalance;
                //updated in inner scope still updates the outer var
		lastlockerbalance=$scope.lockerbalance1[0].LOCKERBALANCE;
		console.log(lastlockerbalance);
	    })

console.log(lastlockerbalance);

The alt. is to extend an object that is declared outside the scope (pretty much the exact same thing if you understood the scope and dom:

var   item = {}; //declared in outer scope so in available in outer & inner scope.
var getlockerbalance=function(){
	$http.get("php/selectLOCKERBALANCE.php")
	    .success(function(lockerbalance){
	        $scope.lockerbalance1=lockerbalance;
                //simply add a property to the item object
		item.lastlockerbalance=$scope.lockerbalance1[0].LOCKERBALANCE;
		console.log(lastlockerbalance);
	    })

console.log(item.lastlockerbalance);

Please don't make a habit of doing the second version. If you do then you should always declare the objects property first:
var item = {lastlockerbalance:null};
or
var $scope.item = {lastlockerbalance:null};

hope that helps
Andy ^_^