Magento 2 - Generate custom log

Put below code in anywhere in magento2 :- $writer = new \Zend\Log\Writer\Stream(BP . '/var/log/custom.log');$logger = new \Zend\Log\Logger();$logger->addWriter($writer);$logger->info("Product Info ". $product->getSku() . "----- Id  ". $product->getId() );

Or you can try this :
file_put_contents(BP . '/var/log/events.log', "$eventName\n", FILE_APPEND);