Just deposit the US dollar bills and transfer them to someone else's US dollar account. Cash dollars can be transferred to someone else's cash dollar account, but cash dollars can't be transferred to someone else's cash dollar account, only to another cash dollar account of the same person. If you must transfer it to someone else, you can only withdraw US dollar cash from your cash account and transfer it to someone else's US dollar cash account.
Domestic individuals can use foreign exchange or RMB to make overseas financial investments such as fixed income and equity through banks, fund management companies and other qualified domestic institutional investor.