Could there be a machine that allows you to talk on different frequencies like the radio wave level or is this magitech? Also would it be an invaluable tool for spies?
If I understand your question right, you want to be able to talk directly with someone on a frequency that is entirely between the two of you. No one else should be able to access that conversation without being on the same frequency. Is that what you hope to achieve?
If so, the several versions of the machine do exist, and it starts with the humble walkie-talkie, climbing all the way up the tech ladder to the smartphone of today. Ta-dah!
Are you talking about a radio? It has a very large range of frequencies. If you mean a non-radio wave frequency, then also yes. Your TV remote or other similar controllers often use infrared light, which is a significantly higher frequency light wave. There isn't really anything stopping you from going to higher frequencies. but they have increasing energy requirements to produce, and are more likely to be blocked by obstacles.