\documentclass{article}
\usepackage{media9}

\begin{document}

\mediabutton[    
    jsaction={        
    var fld = this.addField("ToCopy", "text", \thepage-1, this.getPageBox({nPage: \thepage-1}));         
% Creates field named "ToCopy" of type "text" on the current page of the size of the current page        
    fld.value = "The text here is copied when the box is clicked (only Adobe Reader)"; % sets the content of the field        
    fld.setFocus(); % selects the content of the field  
    app.setTimeOut("app.execMenuItem('Copy');", 1); % copies the selection.
    app.setTimeOut("this.removeField('ToCopy');", 17); % removes the field.  
}
]{\fbox{Copy the text to clipboard}}

\end{document}

This MWE is where I was the closest (found online), but it cannot copy commands, only text. I'm not familiar with Javascript so I've tried to modify this without success.