VCs are paid in two ways:
1) Management fees. 2%/year of funds under management is common. (Over the ~10yr life of a fund, that's ~20% of the capital.)
2) Carried interest. This is a share of the profits on the fund before the money is returned to investors. The typical number here is 20%.
So, let's imagine a fictional $1B fund. Here's how the numbers might work out.
Y-0: Fund is raised. VC contributes $10M for 1% of the fund.
Y-0: 2% management fees are used to cover expenses / pay VCs.
Y-1~2: Fund invests in stuff, takes additional 2% management fees every year.
Y-2~9: Fund is depleted for new investments. Continues to take 2% management fees every year.
Y-10: Fund's last investments exit. Overall, the fund returns a 50% profit ($1.5B, with $500M in profit). VCs take $15M for their original contribution, and an additional $100M in carried interest. So far, they've also taken $200M in management fees (2% a year for 10 years). Total profit: $305M.