Intuitive music composition software

For a class I have to compose soundtracks and music, and I have no experience whatsoever.
Okay, I played classical guitar for a decade but I never was good at music theory and can barely read notes.

My issue is that I come up with a tune, and I need to dump that information to a recording medium as soon as possible. Translating that tune into a short term memory and playing it out on my guitar doesn't work, as I'll end up forgetting it nearly instantly. The one instrument that I can play is whistling, but that's kinda hard to do for long.

I'm looking for a more intuitive way to input notes into a computer.
I was thinking of some kind of pitch slider that continuously plays a note (limited to notes, no microtones) that I can control with an external input device like a knob or potmeter / by moving my mouse up and down, and then hit a button to input that sound, moving on to the next note. No delays inbetween, just immediately starts playing a new note.

Like the computer whistling a note for me, and me adjusting the pitch and length.

I can move my mouse quite precisely & can adjust pitch pretty easily when whistling, it's just that translating music from head to an instrument will never be as intuitive as something like whistling.

It's not supposed to be perfect, on-point music, just enough to record the vague idea and process it later. It also should be super minimalistic, I'd preferably only have the slider, the play/pause button, the confirm note button and a "save to file" button.

I'm not sure where I can even start finding something remotely related to this. I've looked around and tried a bunch of music software, but it's all either complicated or unintuitive.

Anyone know something like this?

Edit: As this website puts it;

Intuitive music composition requires that you hear the musicality of the music as you are composing it. Which means that you have no choice but to compose by playing.

and

You cannot intuitively compose music by entering note data into a software application.