/*
 Theme Name:   Woodmart Child
 Description:  Woodmart Child Theme
 Author:       XTemos
 Author URI:   http://xtemos.com
 Template:     woodmart
 Version:      1.0.0
 Text Domain:  woodmart
*/
add_filter('get_search_form', 'my_search_form_text');
 
function my_search_form_text($text) {
     $text = str_replace('value="Search for products"', 'value="Click me"', $text); //set as value the text you want
     return $text;
}