Edit in JSFiddle

angular.module('myApp', [])
.controller('ParentCtrl', ['$scope', function ($scope) {
$scope.message = "Some text in parent";
$scope.$on("update_parent_controller", function(event, message){
$scope.message = message;
});
}])
.controller('ChildCtrl', ['$scope', function ($scope) {
$scope.clickFunction = function() {
$scope.message = "Parent updated";
$scope.$emit('update_parent_controller', $scope.message);
}
}]);