How do I get child support from my son's father if he is in Haiti because he got deported?

Generally, the best group you would want to reach out to for this is the Family Support Division. The Family Support Division can help you or your family with food stamps, health care, child care, child support, and other needs. Here is a link to their page https://dss.mo.gov/fsd/ Communication of information by, in, to or through this Web site and your receipt or use of it (1) is not provided in the course of and does not create or constitute an attorney-client relationship, (2) is not intended as a solicitation, (3) is not intended to convey or constitute legal advice, and (4) is not a substitute for obtaining legal advice from a qualified attorney. You should not act upon any such information without first seeking qualified professional counsel on your specific matter.

It's unlikely you can get it since Haiti is not required to abide by the orders of a US court. Should the father ever return to the US he will be liable. Otherwise, don't plan on seeing any of it unless he voluntarily agrees to send it.