\documentclass{article} \usepackage{mathtools} \begin{document} $\xrightarrow[\text{world}]{\text{hello}}$ $\xRightarrow[\text{world}]{\text{hello}}$ \bigskip $\xrightarrow[g(x)]{f(x)}$ $\xRightarrow[g(x)]{f(x)}$ \end{document}