mariadb takes too much load though having sufficient RAM I am facing more CPU usage for my app server. Server configuration is as below. 

1&gt; CPU: Intel(R) Xeon(R) CPU E5-2650 v4 @ 2.20GHz 8 core
2&gt; RAM: 32 GB
3&gt; 600 GB SSD NVRAM
4&gt; Mariadb version 10.3.17. 
5&gt; OS: Debian 9


I have run mysql tuning script to optimize server performance and add some parameter in my.cnf. But yet it's not creating big impact. 

I can see that RAM used very less compare to CPU. How can I balance in both and improve server performance?

Here is my tuner script output tunner.
Here is current my.cnf output on my.cnf
With your limited information posted, suggestions to consider for your my.cnf [mysqld] section

max_connections=512  # from 2000 because max_used_connections only 213
join_buffer_size=256K  # from 20M to reduce RAM required per connection
read_buffer_size=256K  # from 2M to reduce RAM required per connection
read_rnd_buffer_size=128K  # from 8M to reduce RAM required per connection


These changes will significantly reduce your CPU busy and provide better performance.