Great question! The US constitution, since it was written in 1787, has been an incredibly powerful and influential document—and not just in the US. Many of the principles of our constitution, like the separation of powers and bill of rights, appear in other countries' governmental documents. For example, South Korea has 3 branches of government (executive, legislative, and judicial), which is what is laid out in the US constitution. South Africa adopted the idea of federalism, wherein the federal government shares power with the states/provinces. The UN also borrowed some language from our constitution when they say that "all human rights are born free and equal."
However, some have argued that the influence of the US constitution is waning in recent years. While the idea itself of adopting a Constitution might stem from the US system, many countries' constitutions now include far more rights than the US constitution, such as women's rights or healthcare. Additionally, the US constitution is one of only 3 that include the right to bear arms (Guatemala and Mexico being the other 2). While the US constitution is decreasing in influence, one study found that the Canadian constitution is now the most widely emulated by other nations. It includes more rights than the US version and was revised more recently, in 1982.