<p>Nuclear magnetic resonance (NMR) is a powerful tool for probing molecular structure and dynamics, but conventional high-field systems are bulky and suffer from field inhomogeneities. Zero- to ultra-low-field (ZULF) NMR overcomes these limits by exploiting internal spin interactions in a magnet-free, shielded environment. When combined with nitrogen-vacancy centers in diamond, it enables a compact, portable platform with high spatial resolution and broad bandwidth for noninvasive chemical sensing in microscopic volumes and real-world settings. We report detection of zero- to ultralow-field nuclear magnetic resonance (ZULF NMR) signals at frequencies of a few hertz using a diamond magnetometer. The sensing diamond is a truncated pyramid with 180 <i>μ</i>m height and a 500² <i>μ</i>m² base. The minimum stand-off distance is &lt;1 mm, and the sensor sensitivity is 13 pT/<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\sqrt{Hz}\)</EquationSource> <EquationSource Format="MATHML"><math> <msqrt> <mrow> <mi>H</mi> <mi>z</mi> </mrow> </msqrt> </math></EquationSource> </InlineEquation> at frequencies <i>f</i> above 5 Hz with 1/<i>f</i>-like behavior at lower frequencies. NMR signals were generated via signal amplification by reversible exchange (SABRE) parahydrogen-based hyperpolarization resulting in zero-field signals at 1.7 Hz and 3.4 Hz corresponding to the expected hetero-nuclear <i>J</i>-coupling pattern of acetonitrile. This work demonstrates a magnet-free platform for detecting chemically specific NMR signals paving the way for portable noninvasive diagnostics in microscopic sample volumes for biomedicine, industrial sensing through metal enclosures.</p>