1) First of all you need Bitcoin and Ethereum wallets. I prefer to use https://blockchain.com wallet but you can use all wallets that you like.
2) You need to have at least ~ 35$ Bitcoin (min. 0.005 BTC) at your wallet.
3) Then you need to exchange 0.005 BTC to ETH using exchanger https://btcswap.online on course 0.005 BTC - 0.234 ETH
How to exchange here:
1. Fill the form and click "Exchange"
2. You will see the BTC address of exchanger where you should send specified amount of BTC from your wallet (don't forget about commission for transaction in BTC network about 0.08$)
3. You will receive Ethereum after the 1st confirmation of BTC network.
4) Now you exchange Ethereum to Bitcoin using exchanger https://coinswitch.co on course 0.234 ETH - 0.0073 BTC
5) So you have 0.0023 BTC (more than 17$) profit per one circle of exchange!
6) If you start with a larger amount of BTC - profit will be higher.