If you want to invest less than 1 BTC, you can go to the S9 or S7 hash market and purchase as little as 1 GH for a little under 18000 sats.
I was able to purchase a hash rate thinks. Mind asking if how much hash power do you have? and when can i possibly(estimated time) get my ROI? a month? or more? or less?
I have the Pacmic contract. So 120 days, if I decide to cash out for that. (I'm reinvesting my profit right now.) I have 150 GH S9. I'm not sure what the ROI on that is. I did not ROI on the S7, when I had it last year. Could take 6 months to never on the S9, depending on the BTC market and the difficulty increases for the BTC network.