How can one maintain the original capitalization when replacing a search term in a string using PHP?

When replacing a search term in a string using PHP, one can maintain the original capitalization by first storing the original capitalization of the search term, replacing all occurrences of the search term in the string with a lowercase version, and then using the stored original capitalization to replace the lowercase version with the correct capitalization.

$searchTerm = "SearchTerm";
$string = "This is a SearchTerm example with SearchTerm in it.";
$lowercaseSearchTerm = strtolower($searchTerm);
$string = str_ireplace($lowercaseSearchTerm, $searchTerm, $string);
echo $string;