Source

.getCurrentHeading
$cordovaDeviceOrientation
  .getCurrentHeading()
  .then(function (orientation) {
    // success, use orientation
  }, function (err) {
    // error
  });
.watchHeading
var options = { frequency: 3000 };
var watch = $cordovaDeviceOrientation.watchHeading(options);
watch.promise.then(
  function () {  /* unused */ },
  function (err) {
    // error
  },
  function (motion) {
    // motion with constant updates
  });
.clearWatch
// use watch.watchID from watchAccelaration()
$cordovaDeviceOrientation
  .clearWatch(watch.watchID)
  .then(function (result) {
    // success
  }, function (err) {
    // error
  });