I am not sure if you have heard of google. It is this website that lets you search the internet based on keywords.

I searched "borrow against bitcoin" and the first three non-ad results were:
https://saltlending.com/
https://coinloan.io/
https://lendabit.com/

I have not done any kind of due diligence on any of the above companies. You will need to research any company you decide to use before entrusting them with your money.

I am also still confused why you would not just use USD, or even DAI to purchase your investment.