Combine chickpeas with vegetable stock in a multi-functional pressure cooker (such as an Instant Pot®). Close and lock the lid. Select high pressure according to manufacturer's instructions; set timer for 35 minutes. Allow 10 to 15 minutes for pressure to build.
Release pressure carefully using the quick-release method according to manufacturer's instructions, about 5 minutes. Unlock and remove lid.
Strain chickpeas, saving 150ml of the liquid. Place chickpeas in the bowl of a food processor; add lemon juice, tahini, olive oil and garlic. Blend until smooth and creamy, about 3 minutes. Scrape bowl and add reserved liquid, cumin and salt; blend for 1 minute more.