Some small laptops have a 'combo audio jack' as here:
https://support.lenovo.com/gb/en/solutions/ht103046

You can get adapters that break out the connectors, as it shows.

Mind you, you then only get a microphone jack, with all that implies for sensitivity and equalisation . If you want a proper line-in socket you probably need a USB 'sound card'.

FWIW I have an 'Terratec Aureon 5.1 USB' - which I bought on eBay and works with Linux. When I bought that there were cheap ones, e.g. from Soundblaster, that work with Windows.