Lenovo makes their own desktop computers, but for notebooks, they are mostly made by Taiwanese companies in China.
Currently Taiwanese companies makes the R, X, and Z series for Lenovo.
As for T-series, when IBM still owned the thinkpad brand, they were made under IBM and Great Wall Technology joint venture. This is because T-series was IBM's most important line of notebooks, so they keep an eye on it through joint venture.
Now that Lenovo bought over the IBM Thinkpad brand, I don't know if it was still made with Great Wall Technology, since Great Wall Technology is a competitior of Lenovo.
As for Apple, Taiwanese companies has been making computers for them for a long time.