In German, there is an idiom "Hier spielt die Musik!" (with intonationally emphasized "hier"). Translated literally: "Here is the music playing!" It is used with an accompanying pointing gesture to direct/point someone's attention to oneself or to a specific point in space/location. It is mainly used to grab someone's attention, or to regrab her attention because the person had become distracted by something else.
In plain words, you could say: "Look here/at me (again)!", "Listen to me (again)!", or more generally (but less correct): "Pay attention to here/me (again)!"
Does an idiom with the same function exist in English?
If you are a native speaker and not aware of such an idiom then an answer like "I am a native speaker and not aware of such an idiom" is absolutely fine and will be highly appreciated.
Best Answer
I think I understand what you're trying to convey: if someone is distracted or ignoring you while you're speaking, a simple way to get their attention in English would be by simply saying "Hellooo?" (focus on a inquisitive intonation) and/or "Over heeeree" (again, all in the intonation) accompanied with waving or snapping fingers, but be warned these are not very elegant approaches. A politer way would be by simply saying "Excuse me?" to get their attention again. Good luck!