I never tried those USB to guitar jack cables, but the cheapest option I‘ve ever used for (very rudimental) idea collection was going from the guitar into the mic in of my sound card. All you need is a 6,3mm to 3,5mm adapter like this: but be aware that you’ll have to digitally amplify your sound which can become quite noisy. YMMV though. If you want to take the safe route I‘ld recommend to get an interface. You won’t need anything fancy if you‘re not going for studio quality. Something like the Behringer Uphoria works well enough and won’t cost you more than 20€ used usually. I would always go for an USB interface as they also serve as a direct monitor so you won‘t hear yourself delayed when recording. Hope this helps and let us know what you chose and if it works out for you!