OPcacheの導入方法は環境毎に異なるので割愛しますが、以下のようにopcache.enable => On => OnとなっていればOPcacheは有効になっています。
$ php -i | grep opcache
Additional .ini files parsed => /etc/php.d/10-opcache.ini,
opcache.blacklist_filename => /etc/php.d/opcache*.blacklist => /etc/php.d/opcache*.blacklist
opcache.consistency_checks => 0 => 0
opcache.dups_fix => Off => Off
opcache.enable => On => On
opcache.enable_cli => On => On
opcache.enable_file_override => Off => Off
opcache.error_log => no value => no value
opcache.file_cache => no value => no value
opcache.file_cache_consistency_checks => On => On
opcache.file_cache_only => Off => Off
opcache.file_update_protection => 2 => 2
opcache.force_restart_timeout => 180 => 180
opcache.huge_code_pages => Off => Off
opcache.interned_strings_buffer => 8 => 8
opcache.lockfile_path => /tmp => /tmp
opcache.log_verbosity_level => 1 => 1
opcache.max_accelerated_files => 10000 => 10000
opcache.max_file_size => 0 => 0
opcache.max_wasted_percentage => 5 => 5
opcache.memory_consumption => 128 => 128
opcache.opt_debug_level => 0 => 0
opcache.optimization_level => 0x7FFEBFFF => 0x7FFEBFFF
opcache.preferred_memory_model => no value => no value
opcache.preload => no value => no value
opcache.preload_user => no value => no value
opcache.protect_memory => Off => Off
opcache.restrict_api => no value => no value
opcache.revalidate_freq => 2 => 2
opcache.revalidate_path => Off => Off
opcache.save_comments => On => On
opcache.use_cwd => On => On
opcache.validate_permission => Off => Off
opcache.validate_root => Off => Off
opcache.validate_timestamps => On => On