So in my case is it safe to use PBKDF2 as hashing tool - to hash any thing like (timestamp+sensitive_info+extra_info) with a SECRET_KEY just similar to hmac?
The reason that a Password Based Key Derivation Function or password hash is used is because passwords are generally not considered secure enough. The iterations or work factor of such a PBKDF makes it harder for attackers to use dictionary attacks and the like to retrieve the password value and any derived key from it.
However, if you already have a secure secret key then there is no need to perform PBKDF2. It doesn't depend on the sensitivity of the protected data at all. So if you have a secret key and you just need integrity and authenticity, then you can just use a normal MAC - such as HMAC. If you also need confidentiality then an authenticated cipher such as GCM makes more sense.
Beware that HMAC doesn't have a salt; you may need a nonce or IV value to make your message / ciphertext secure (but this depends on the threat model for your particular use case). If you use a timestamp then this may be part of providing message uniqueness (although timing information is always a bit dangerous due to precision and reset issues).