I am running Mint Debian on a ThinkPad T440P, and I want to record audio with Audacity via the combo jack. I used a standard 3.5mm stereo cable connect to the cassette player but I can't get the audio, I believe it was the combo jack not wired that way and shorted the contacts so need an adapter that I don't have. Then I used an USB multi adapter with audio to try, this time I can see the input device on the system sound setting and got signal from it, but it simply noise. Since the USB adapter is type C for newer notebook. so that may not support older notebook or other reasons I don't know, any comment ?

Correction, MINT can only see additional output devices, no change on input device except the on board mic, so that the adapter does not support audio input

The 3.5 mm audio in a laptop is a 4 wire headset with microphone. The cassette output is line level which is the wrong impedance. You probably don't have the right cable but it doesn't matter. Although need to check the specs. It might be a combo port.

If the USB audio input adapter does not accept line level input then it isn't going to work.

I found an old PC with separate in and out port so problem fixed, thanks. Audio level is too high but the mic port sounds better than line in, I still able to turn down the level not to distort. Btw, adding to the problem was modern cell phone with different wiring on the handsfree jack, and many people mixed use of those with standard PC type.