If I use a MacBook Pro to mine Bitcoin (and keep records for the blockchain), how much can I earn in 1 month? I know people say it is not practical to mine Bitcoins using a computer any more, but graphics cards are usually used to mine them.
But suppose just for fun, I do use a MacBook Pro to

mine it 8 hours a day, and also
participate to be part of the blockchain to keep records

How much can I earn per month doing #1 and #2 above, even if it is just a few dollars?  Can I really download some software to do #1 and #2?
It will be hard to find exact numbers, as GPU mining for Bitcoin has been completely obsolete since somewhere in 2013 when the first ASIC-based mining solutions appeared.
Still, I wouldn't expect the CPU and GPU in a modern Macbook Pro to be able to mine faster than a few 100 million hashes per second. Even if we assume it can do 1 billion hashes per second (probably a serious overestimate), then as of January 2021, with 8 hours/day, you'd make around 0.002 USD per month in a pool (if they even permit you withdraw such a small amount). If not in a pool, it'd be exactly 0.
It won't be worth the added cost in electricity. It won't even be worth the cost in added wear &amp; tear to your hardware.
There probably exists software that can do this still, but I don't expect it to be maintained or easy to set up as it has been obsolete for so long.