Help: sound of the metronome in the headphones

How do I get the sound of the metronome in the headphones when running? 
Musik and all metrics (tempo, pulse zone) - everything says in the headphones,
but the metronome beeps only on the hand, not in the headphones...
I want to train my cadence, so I turn on the metronome,
but its squeak is very quiet and I can’t hear it
( do not turn on the vibration, annoying).
What do I need to do so that the sound of the metronome is broadcast to my headphones?
Thnx!
PS I don’t listen to music when running,
I just gave an example that broadcasting to headphones works