Implant tools and techniques for implanting implantable medical leads or other implantable components in extracardiovascular locations, such as substernal locations, are described. In one example, the present application provides an implant tool for implanting a medical lead comprises a handle and a shaft. The shaft includes a proximal segment that is permanently coupled to the handle and a distal segment that is detachably coupled to the proximal segment. The distal segment includes a proximal end configured to couple to the proximal segment, a distal end, and a lumen extending an entire length of the distal segment from the proximal end to the distal end. In some instances, the implant tool may be part of a delivery system that includes a puncturing tool having a proximal end and a distal end, wherein the distal end is sharp, such as a syringe coupled to a needle.