I don't know for sure, but somewhere in the OS settings (or perhaps somewhere in some Lenovo utility program) there could perhaps be an option to configure the 3.5 mm jack as either headset, line-in, microphone, line-out, headphone, whatever port. If there is no such setting to be found, try a 3.5 mm microphone+headphone to headset adapter (converting two individual 3.5 mm jacks to a single 3.5 mm headset plug).

If you don't like spending the four or five bucks these things cost, there is also the option of measuring the length of the contacts on a 3.5 mm headset plug (if you have a headset with such a plug), and trying to tape off the areas of the microphone plug that would overlap the headphone contacts on the headset plug. If none of the suggestions work, there is always the option of last resort of borrowing a hammer from the friendly neighbor and. solve. the. problem. once. and. for. all.

(A side note: I don't want to ask how/why you would think there are two 3.5 mm jacks -- but no, on the photo you drew the big fat green arrows on it is very clearly visible that there is only a single 3.5 mm jack...)