Mein LaTeX-Forum

\documentclass[parskip=half,ngerman]{scrartcl}
\usepackage[T1]{fontenc}
\usepackage{babel}
\usepackage{mathtools}

\begin{document}
  Der Spitze"=Tal"=Wert  \( \overset{\wedge}{\underset{\vee}{u}} \) oder \( U_{\text{ss}} \).
\end{document}

\documentclass[parskip=half,ngerman]{scrartcl}
\usepackage[T1]{fontenc}
\usepackage{babel}
\usepackage{mathtools}

\newcommand{\peak}[1]{%
   \overset{\wedge}{\underset{\vee}{#1}}
}

\begin{document}
  Der Spitze"=Tal"=Wert  \( \peak{u} \).
\end{document}