へ行（い）く is a common construction used when describing a place that someone/something is ‘heading’. The particles に and へ are interchangeable, but there is a slight difference in meaning. に has the nuance of ‘going to’, while へ has the nuance of ‘heading to’.

• ジョンは学校（がっこう）へ行（い）く。
  John is heading to school.
• エルサは病院（びょういん）に行（い）く。
  Elsa is going to the hospital.

In these examples, while they may seem the same at first glance, へ focuses much more on the journey, while に puts more emphasis on the destination. This is true for other uses of に and へ as well. に will always put more focus on the destination of an action, where へ will put more emphasis on the distance traveled/between the origin and destination.

• 先生（せんせい）へ電話（でんわ）をする。
  To make a call to the teacher. (Focuses more on the distance between the caller and receiver)
• 先生（せんせい）に電話（でんわ）をする。
  To make a call to the teacher. (Focuses more on the destination of the call)