There are various ways in order to acquire Bitcoin or an amount of it perhaps, and investing or buying is the easiest way, I think to do so. In order for an individual to invest to it ,one could use exchanges or cryptowallets. There are options, as the previous posts have mentioned,that allows an individual to convert fiat(currency which has a physical form) to crypto( general term referring to different coins including Bitcoin).

You may also buy an amount from other investors or users but using exchanges and wallets would be a lot easier.