You may find an example in the public function getCode () of template\scripts\BxBasePage.php class:

$oCache = $this->_getPageCacheObject();

            $sKey = $this->_getPageCacheKey();

            $mixedRet = $oCache->getData($sKey, $this->_aObject['cache_lifetime']);

            if ($mixedRet !== null) {

                $sPageCode = $mixedRet;

            } else {

                $sPageCode = $this->_getPageCode();

                $oCache->setData($sKey, $sPageCode, $this->_aObject['cache_lifetime']);

            }